refactor(danmuku): [PKG-DANMUKU-04] own scheduler and worker request lifecycle

packages/artplayer-plugin-danmuku/README.md

@@ -20,11 +20,31 @@ reject the corresponding public `load()` Promise. Initial automatic loading
 observes its rejection and logs a warning. XML Worker startup/runtime failures
 use the existing parser locally and release Worker/Blob resources.
 
-Explicit `time: 0` is preserved. A replacement callback passed to `config()`
-takes effect, and invalid configuration leaves the current option intact.
+Explicit `time: 0` is preserved. Missing time and `NaN` retain the historical
+default of the current playback time plus 0.5 seconds. Positive infinity remains
+unchanged; negative values, including negative infinity, are clamped to zero.
+A replacement callback passed to `config()` takes effect, and invalid
+configuration leaves the current option intact.
 Existing method return identities, getters, input normalization and XML fields
 remain compatible. Configuration changes do not automatically reload data.
 
+## Scheduling failures and recovery
+
+Playback uses one scheduling loop. Pausing, seeking, hiding, resetting or
+destroying the player cancels unfinished visibility preparation. Updating
+`beforeVisible` also releases an unfinished old callback; seeking and callback
+changes preserve already displayed comments.
+
+A rejected `beforeVisible` emits the original `artplayerPluginDanmuku:error`
+once for that item in the current run, while other items continue. It is not
+retried every frame. Pause/resume, reset or a replacement callback permits a
+retry if the item still matches the display-time rules. A track Worker failure
+reports once and halts scheduling until pause/resume or reset rebuilds it.
+
+If an error listener synchronously stops, destroys, resets or hides the instance,
+the interrupted recovery respects that action. A nested start can recover once
+without the outer call resuming it again or emitting another start event.
+
 See [ARCHITECTURE.md](./ARCHITECTURE.md) for module ownership, compatibility
 constraints, tests and the remaining staged TypeScript migration.